here's the deal. i bought a new on from ford earlier this week. i was told these were notorious for going out, and that was the reason for the front differential not locking! when we got into it, we found out that the original pump was working, but something internally was not? I went back to ford, and asked for a refund, but it had marks of install. Anyway, we took the diff, apart and found there was a bearing slide that had broken , and was able to pickup that day! $ well.... $ 189 for the slide arm, and $ 210 for the vacuum pump, its fixed! I'm here to sell the original pump from my truck, that i will garauntee to work for a fraction of the cost of new! i'm asking $ 105 shipped. her is the ford part# for reference! F65Z-3G360-BA I will answer all Q's. thanks PS.. JUST MAKE SURE YOU DONT DO THE SAME THING I DID, AND PURCHASE A EXPENSIVE PART THAT U END UP NOT NEEDING! I CAN SEND PICS IF U LIKE!